Multiple means for applying brakes



Dec. 19, 1944. i I G..KE|TH 2,365,557

MULTIPLE MEANS FOR APPLYING BRAKES Filed Aug. 6, 1942 Patented Dec. 19, 1944 NITED STATES PATENT OFFICE 2,365,557 MULTIPLE MEANS son. APPLYING BRAKES Glenn Keith, East Deana, Mich.

Application August 6, 1942, Serial No. 453,869

(oi. its-ice) l Glaims.

struction is equally applicable to other kinds of vehicles.

In aircraft particularly it is desirable to associate with a normally usable brake applying means an auxiliary means that will automatically go into operation when for any reason the normal means does not operate. It is particularly desirable that no additional effort be required of the pilot to operate the auxiliary means. It is a principal object of the present invention to associate with a. normally usable brake applying means an auxiliary mechanism capable of applying the brakes automatically on continued actuation of a single control element for the two means if the brakes should fail to be applied by the normal means.

The system thus combines an emergency mechanism with what may be a more or less conventional service mechanism. The principal types of service brake applying mechanisms which are at present preferred by the industry are of the fluid pressure type controlled by a pedal which is actuated to increase pressure in a master cylinder and communicate this pressure tobrake cylinpresent invention include two independent means for applying pressure to the brake cylinders. Both means being successively operable upon continued actuation of a single control element, such as a pedal, brake application is possible as long as one of the means remains intact, and since the two means are quite independent and considerably separated up to the point where they join, which is at the wheel to be braked, it is relatively unlikely that any single cause of damage to one of the means will involve any damage to the other.

In the preferred embodiments the construction includes a fluid pressure force normally apders mounted adjacent to the wheels. The master cylinder and the brake cylinders are connected by fluid pressure lines, and it sometimes happens that these lines break or leak. In the case of military aircraft these lines because of their length are quite vulnerable to damage in combat. The brake cylinders themselves occupy relatively small space and are commonly located close to the wheels. For these reasons they are less liable to be damaged.

A further object of the invention is to associate with a normal service brake system an auxiliary or emergency system whose parts are confined wholly to the immediate region of the wheels to be braked, except for electric wire leads connecting with a control element and a battery or other source of current.

- e The preferred constructions proposed by the plicable to the brake cylinder plunger and an electric motive force alternatively or sequentially acting on the brake cylinder.

In the accompanying drawing, which illustrates certain preferred embodiments of the invention applied to an aircraft equipped with a. known type of brake member for each of its braked landing wheels,

Figure 1 is a. side elevational view of the forward portion of an aircraft;

Fig. 2 is a diagrammatic illustration of one type of system proposed by the invention;

Fig. 3 isa similar view of another type of system proposed by the invention;

Fig. 4 is a radial section through part of a landing wheel equipped .with a known type of brake and with either'of the embodiments of the present invention shown in Figs. 2 and 3;

Fig. 5 is an elevational view of a preferred type of variable resistance device which may be used in the system; and

Fig. 6 is a diagrammatic illustration ,of a modified circuit arrangement. Referring now to the drawing, the reference numeral l0 designates a, vehicle, here shown as a conventional type of aircraft having a pair of forward landing wheels ll each provided with any desired kind of brake device, such for example as that shown more in detail in Fig. 4.

This brake device, the specific features of which are known and form no part of the present invention, comprises a stationary torque member or frame I; having a circular peripheral channel l3, recessed within which is an inflatable expander tube I! connected by a nipple I! to a shortfluld pressure line Hi. The tube I4 is normally collapsed but is adapted to expand, upon receiving fluid pressure through the line Ii, against a series of segmental brake shoes II to press such shoes against the drum l8 0! the wheel It- Means may be associated with the shoes for keeping them normally retracted from the drum, such means being shown in the illustrated embodiment of the invention in the form of transverse leaf springs 2b which extend through the shoes and seat in openings in the channel it. An outstanding radial flange 2i extends from the drum and is flared to form a rim 22 for a tire V The present invention provides a chamber 2 3 located closely adjacent to the torque member l2 and connected to the pressure line it for increasing pressure in this line to expand the tube Hi and thus apply the brake.

An important feature of the invention is the provision of two normally independent means for increasing pressure in this chamber, which may be called a brake cylinder. Fig. 2 illustrates one of several forms which these two independent means may take. In this embodiment the chamber is a double cylinder, one cylinder being designated and the other 2%. The two cylinders are set closely together side by side and communicate by means of a port 2? near their lower ends.

The cylinder 25 contains a floating plunger 28 which is normally, when the brake shoes are retracted, positioned at the upper end of the cylinder. From the cylinder head a pressure line 29 extends to a cylinder 38 in the fuselage oi the aircraft; and this cylinder til has a piston 3i carried by a rod 32 which receives rearward thrust from some appropriate control element such as the pedal With a body of brake fluid filling the cylinder 3t and line 29, and another body of brake fluid filling the cylinder 25 and line l6, it will be ob= vious that actuation of the control element will cause the floating plunger 28 to descend and increase pressure in the chamber 26 to apply the brake. This is the normal operation or" the brake applying means.

In the cylinder 2% of the chamber it a plunger 3&- is normally positioned in the head end of the cylinder, which end is perforated to pass a rod 35: for the plunger. This rod has its upper por tion formed of iron, so that it acts as the annature of a solenoid, the coil 3d of which surrounds the rod 35 and is fixed just above the chamber 25, adjacent to the torque member 92, to which it may be secured as by a bracket 68.

It will be obvious that upon the plunger being driven into its cylinder 25, no fluid will pass through the port 2'? and into the cylinder 26 because this cylinder is effectively closed by its plunger (it. It will also be apparent that if the plunger 3 is driven into its cylinder 26, no

vfluid will pass through the port 2? because the cylinder 25 will be effectively closed by its plunger 28. Thus, if the plunger 53 3 is driven into the cylinder 26, as by energization' of the coil 88,

the brake will be applied by the resulting increase of pressure in the chamber 2 3.

The coil 36 is connected by electric wires 3? and 38 with a switch 39 and a battery or other cation Serial No.452,050, filed July 23, 1942. As

more particularly shown in Fig. 5, it includes a stationary resistance winding '33 engaged by a contact i l carried by the free end of a bimetallic coiled element 65. Shoes it on the opposite ends access? of the resistance winding 63 afford convenient means of calibrating the device to include more or less of its coils. The device is arranged so that the contact 36 is initially engaged with the outer shoe dB or with a coil of the winding 63, so

that a conductive path is established through the device. When the circuit including this path is completed, as by closing the switch 3%, the coil 65 expands in response to heating and its contact i l moves toward the shoe t6 so as progressively to cut out more of the coils of the winding and thus decrease the resistance offered by the device. In this way an initially feeble currentbuilds up to one of greater strength, so that the coil 36 becomes increasingly energized if the switch 3% is closed. It. will be observed that this will have the effect of gradually and progressively increasing the braking force applied to the drum it.

The switch it is positioned so as to be engaged and closed by the control element 33 when the latter is actuated further than the initial range which is required to apply the brake by action of piston ill in cylinder til; The system may be arranged so that the switch 39 will not be closed by the element 33 unless no sumcient braking effect is produced by movement of the piston in which case the electrical portion of the system will be a purely emergency agency which will not be called on to function if the service agency operates. l-lowever, if desired, the switch may be arranged to be closed by the element before that element reaches the end of its stroke neces= sary to produce full application of the brake, which case the electrical agency will perform the function of an auxiliary or booster device.

The system shown in Fig. 3 is very similar to that of Fig. 2. It difiers principally in that in it the chamber 26 is a single cylinder 56. Like the double cylinders 25 and 26, this cylinder St is connected at its bottom to the line it and it contains, normally at its head end, a single plunger hi the 7 rod 52 of which extends out through a supple- Eli down into the cylinder 5b to cause the brake to be applied. Energizationof the coil 55 will similarly thrust the plunger 59 down into the cylinder 59 to cause the brake to be applied. It willbe appreciated'that the system is operated by the pilot in exactly th same way as the system shown in Fig. 2 and that the two systems embody the same (iii substantial principle.

The Fig. 3 embodiment has the advantage of occupying smaller space and comprising some- What fewer parts, but the Fig. 2 embodiment has the advantage of dispensing with the packing 'means required in Fig. 3.

Of course, in any embodiment of the invention the brake devices for each of the brake-equipped wheels are connected in parallel, as by arranging plural lines 29 branching from the cylinder 36 and leading to each chamber 25, and by connecting the coils or the like 36 or 55 in parallel with the circuit including the switch battery or the like ill, and resistance device ii if such be included.

It is to be understood that no resistance device accuser 45 or its equivalent need be included in the system unless it is desired to prevent sudden, full-power application of the brakes upon closing the auxiliary or emergency circuit. Of course any other means for producing gradual and progressive increase of braking effect may be substituted.

The solenoid devices shown as comprising the electric motive means of the system are illustrative merely, and may be replaced by any other kind of electrically operated or controlled brakeapplying means.

In some cases, to suit the preference of some pilots, it is desirable to substitute a rheostatic circuit closer for the simple type of switch shown at 39. Such an arrangement is shown in Fig. 6 where the element which is movable in response to depression of the pedal or the like 33 carries a member 69 which comes into engagement with and wipes the windings of a resistance element Bl so as progressively to increase the value of the current flowing through the circuit including the battery 39 and solenoid 36 as the pedal is further depressed. This of course will eliminate the need of the resistance device 4| since it will enable the pilot to control directly and at will the value of the braking efiect. It has the advantage, which is highly regarded by some pilots, of giving the I pilot the feel of the brakes as they are being applied. That is to say, with such a system the pilot directly feels the effect of electrical application of the brakes as he progressively depresses the pedal, just as he directly feels the effect of mechanical application during the initial movement of the pedal. 7

It is expected that in each installation of the system shown by the drawing, including the variable resistance device ill or its equivalent, such device will be accurately calibrated or adjusted to bring the particular vehicle to a stop in the shortest time or running distance possible, or in such time or distance as may be thought best for the particular vehicle. Of course if a rheostatic circuit closer be substituted, stopping time and distance will be a matter for the pilot to decide each time the electrical system is energized.

Other specific embodiments are contemplated but it is believed that the two herein disclosed are sufiicient to exemplify the principles of the invention. These principles are regarded as of broad application, and all modifications of the disclosed constructions which embody these principles as defined by the appended claims are to be regarded as within the scope and purview thereof.

I claim:

1. A vehicle braking system comprising a brake member, a fluid pressure chamber connected to the brake member for applying the same, a brake control element, a fluid pressure cylinder con-' nected to said element and .to said chamber so that upon initial actuation of the element pressure inthe chamber will be increased, an electrical device also connected to the chamber and adapted when energized to increase pressure in the chamber, and a switch adapted to close a cir-' cuit including said electrical device and a source of current when the brake control element is further actuated.

2. A vehicle braking system comprising a wheel and a brake member cooperating therewith, a fluid pressure chamber adjacent to the wheel and connected with the brake member to apply the same upon increase of pressure in the chamber, means for increasing pressure in the chamber comprising a fluid cylinder, a fluid line connecting the cylinder to the chamber, and a control element normally initially actuatable to increase pressure in the cylinder for communication to the chamber, and means operable in an emergency, upon further actuation of the control element, for increasing pressure in the chamber independently of the cylinder andline.

3. A vehicle braking system comprising a wheel and a brake member cooperating therewith, a fluid pressure chamber adjacent to the wheel and connected with the brake member to apply the same upon increase of pressure in the chamber, means for increasing pressure in the chamber comprising a fluid cylinder, a fluid line connecting the cylinder to the chamber, and a control element normally initially actuatable to increase pressure in the cylinder for communication to the chamber, and means operable in an emergency, upon further actuation of the control element, for increasing pressure in the chamber, said last named means comprising a plunger in the chamber, an electric device for moving the plunger to increase pressure in the chamber, and a circuit including the electrical device and a switch adapted to be closed upon said further actuation of the control element.

4. In a vehicle wheel braking system, .a fluid pressure brake-applying chamber mounted adjacent to the wheel, plunger means in the chamber, a fluid pressure cylinder, a fluid line connecting the cylinder to the chamber; a piston in the cylinder, a control element adapted to drive the piston when the element is initially actuated, a switch adapted to be closed when the element is further actuated, a source of current and an electric motive device in circuit with the switch,

. and means connecting the electric motive device with said plunger means whereby actuation of the control element operates to increase pressure in the chamber, initiallythrough the medium of the cylinder and line and finally through the medium of the electric motive device.

5. In a vehicle wheel braking system, a fluid pressure brake-applying chamber mounted adjacent to the wheel, a pair of plungers in the chamber, a fluid pressure cylinder, a fluid line connecting the cylinder to the chamber for conducting fluid under pressure from the cylinder to one of the plungers to increase pressure in the chamber, a piston in the cylinder, a control element adapted to drive the piston when the element is initially actuated, and independent electrical means, operable when theelement is further actuated, for electrically operating the other plunger in the chamber to increase pressure in the chamber.

6. In a vehicle wheel braking system, a fluid pressure brake-applying chamber mounted adjacent to the wheel, a pair of plungers in the chamber, a fluid pressure cylinder, a fluid line.

other plunger to increase pressure in the chamber.

'7. In a vehicle wheel braking system, a fluid pressure brake-applying chamber mounted adiacent to the wheel, a pair of plungers in the chamber, means including a control element for applying fluid pressure to one of the plungers when the element is initially actuated, means including'an electric circuit for driving the other lunger, and means for closing said circuit when the element is further actuated.

a. In a vehicle wheel braking system/a fluid 5 pressure brake-applying chamber mounted adjacent to the wheel, a pair of plungers in the chamber, means including a control element for applying fluid pressure to one of the plungers when the element is initially actuated, an armature connected to the other plunger, an electric device for applying force to the armature, and

means for energizing the electric device when the access? one of the plungers and means including-an electric circuit for driving the other plunger, and a single control element adapted when initially actuated to apply iiuid pressure to the first named plunger and adapted when -further actuated to close said electric circuit to drive the other plunger.

10. In a vehicle wheel braking system, a fluid pressure brake-applying cylinder mounted adjacent to the wheel, a plunger in said cylinder, 9, rod connected to the plunger and projecting from the cylinder, means for conducting fluid pressure to th back of the plung'er to drive the plunger into the cylinder, electric means operative on the rod to drive the plunger into the cylinder, and a control element adapted when initially actuated to increase pressure in the conducting means and adapted when further actuated to close a circuit to the electric means.

11. In a vehicle wheel braking system, a fluid pressure brake-applying cylinder mounted adjacent to the wheel, a plunger in said cylinder, an. armature connected to the plunger and project- 7 ing from the cylinder, means for conducting fluid pressure to the back of the plunger to drive the plunger into the cylinder, a solenoid cooperating with the armature to drive the plunger into the cylinder, and a control element adapted when initially actuated to increase pressure in the conducting means and adapted when further ac tuated to clos a circuit to the solenoid.

12. In a vehicle wheel braking system, a fluid pressure brake-applying cylinder mounted adiacent to the wheel, a plunger in said cylinder, an armature connected to the plunger and projecting from the cylinder, means for conducting fluid pressure to the back of the plunger to drive the plunger into the cylinder, a second cylinder connected to the conducting means, a piston in said second cylinder, a solenoid cooperating with the armature to drive the plunger into the brakeapplying cylinder, and a control element adapted when initially actuated to drive the piston into the second cylinder and adapted when further actuated to close a circuit to the solenoid.

13. In a wheel braking system, a fluid pressure brake-applying chamber mounted adjacent to the wheel, a plunger in the chamber for increas-- ing the fluid pressure therein, a control element for driving said plunger, and mechanism cooperating with the element and the plunger comprising a fluid pressure transmission device operative to drive the plunger when the element is initially actuated and an electric circuit including an electrornotive device, a source of current and a rheostatic circuit closer for progressively increasing the fluid pressure in the chamber after initial actuation of the element.

. 14. In a wheel braking system, a fluid pressure brake-applying chamber mounted adjacent to the wheel, a single plunger in the chamber for increasing the pressure therein, a control element for said plunger, and mechanism cooperating with the element and the plunger comprising a fluid pressure transmission device operable on the plunger when the element is initially actuated and an electric circuit including an electromotive device connected to the plunger, a source of current and a rheostatic circuit closer for progressively increasing the pressure in the chamber after initial actuation of the element.

15. In a wheel braking system, a fluid pressure brake-applying chamber mounted adjacent to the wheel, a, pair of plungers in the chamber adapted to be driven to increase the pressure in the cham her, a control element for said plungers, and mechanism cooperating with the element and the plungers comprising a fluid pressure transmission device operable on one of the plungers when the element is initially actuated and an electric circuit including an electromotive device connected to the other plunger, a source of current and a rheostatic circuit closer for progressively energizing the electromotive device to increase the pressure in the chamber after initial actuation oi the element.

GLENN mu. 

